I checked out the three Disco Demands compilations a week or two ago after looking into the fantastic Million Dollar Orchestra project (which I'm sure I'll post about shortly) and they're almost consistently great. Collections of rare cuts, re-edits and just general classic tunes; rather than featuring the usual disco staples you can almost guarantee that there'll be unheard material for you - I'd only ever heard one of the tracks before out of all 3 compilations.
As a sample of what you can expect, this Firebolts cut is superb. Slap bass, sunshine guitar, joyful stuff.
The Firebolts - Everybody Party (Get Down) (Re-Edit) (MP3):YSI
Another sample, check "How Can I Tell Her" by Curtis which is from the first compilation. If you ever need a song to remind you why you love music, this is it:
You can buy Volumes 2 and 3 on CD for the insanely low price of £3.50 each from their online shop or all 3 collections in MP3 format here Bear in mind that the official store MP3s are 320kps, I transcoded this sample down so as not to annoy anyone!